Kinetico Model 60 Issue with Softness

Im in Arizona, just south east of Phoenix( Gilbert) .
A little background
Ive had a Kinetico Model 60 on the house for a couple years. A friend gave it to me when he moved out of his house and didn't want to take it with him. I would guess that it is about 12-14 years old, but it is virtually perfect condition on the outside at least.
It is plumbed in on the outside of the house in the backyard( behind the block fence) to the main line coming into the house. ( i have a line plumbed from the untreated side that runs to the irrigation and pool which i can adjust)
Its worked pretty well as far as i can tell but in the last recent months i have noticed the the softness of the water has been less and less, and irt seems that it kind of cycles between producing fairly soft water to not soft water at all.
I suspect one tank has very inefficient media( gone bad) and the other is getting there.
I never lose water flow.
If i regenerate each tank a couple times the softness level seems to go back up for up to a couple weeks.

Ive changed the media i a softener before, along with the gravel and dont think it will be to difficult to do in this case.( i understand these dont use a gravel bed) BUT, i want to make sure that is the issue.
what else should i check? ( it seems to function fine as far as cycling and drawing brine).

If nothing of if what i check out proves to be a non issue and i want to replace the media, what is the best media to use and why?
here the TDS is 400-1200
here is a link the water quality report for the town for other information:http://www.gilbertaz.gov/pw/pdf/WaterQualRep2011.pdf

It could be the resin or the disc is not the correct for the hardness of your water. According to my manual, you should have a # 3 disc for your compensated hardness. You can also check the resin to see if it's bad. Get a sample and pinch it between your thumb and finger. If it smashes up or feels like mush, it's bad.

Since the unit was originally sold in this area i would guess the disk is correct, but that said it is 12 + years old, maybe something has changed in the water since then, but AFAIK the water has always been very hard here. Can i tell which disk is there from looking in through the top of the control valve?
Also do the heads just spin off the top of the tanks( to get to the resin?)

I can see a "water meter" wheel in the control head, it has a #2 on opposite sides , those are the only numbers i can see so i presume then it is a #2 disk.
So the question is, how, does that affect the softness level of the water coming out of the unit.

I wont be able to get a resin sample till the weekend( i hope).

Tom Sawyer..
What leads you to think it could be an Iron issue? Is there something in the water report i linked to?

When you have the wrong disc (which you do), the water will be soft after a regen than hard just before the next regen and that is what you have said. With your hardness, the unit should have a #3 disc.

Make sure your toilets are not running or you have a drip anywhere. 0.1 gallons per minute is 244 gallons per day. Water may be passing by the metering turbine without counting the volume. Always check to see if water is moving.
Check to see if you have 15" of freeboard on top of the resins. If you have lost resin volume, you need to replenish lost resin. Better yet, just replace all of it with fresh resin.
I agree, #3 wheel should be used at a 2.7lb. salt setting or #2 at a 4.4lb salt. It might be easier to keep the #2 and increase salt slightly. You should be able to get that wheel at your dealer. Couple of bucks, at most.

Be sure to decrease water pressure to zero before removing lens cover.

Where do i check/see what the salt setting is set to on this Model 60?
Is there anything else i should check while the control head is apart? seals/parts/clogs etc?

I am also curious IF anyone can identify exactly how old this unit is by serial number.
The reason i ask is this, if it is in fact 12-14 years old how likely is it that the resin that is in it, just doesn't come up to par with what is available today, it has been more than a decade, i would think there have been some advancements...maybe not. Obviously if the resin is soft it gets replaced, but im wondering if i should just replace it anyway with a new "current" product.

Which begs the question, which resin,how much( i know to get 8-10% crosslinked, but anything else i should know?) and where to buy it locally (Gilbert AZ)